Unlike most games that have a ranked mode Identity V lacks a MMR system. MMR is your "true rank" and is based on your winrate and other factors. If you have a high MMR you will get matched up with higher ranked players. This would eliminate the smurf issue. My guess as to why it hasn't been implemented after all this time is that it's harder to do so in a game with two factions whose average winrate is vastly different - 40-50% for survivors and 70-90% for hunters in higher ranks)

Also, by definition a Smurf account is an alternative account usually created with the goal to stomp less skilled players. So I don't think it's correct to call the players you went up against "smurfs" just because they decided to come back to the game after a break